1. Field of the Invention
This invention relates to a steering assist device at a parking time in retreat, and particularly relates to a device for superposing and displaying for supporting a steering wheel operation at the parking time on a monitor screen on which the picture of a backward portion of a vehicle is displayed.
2. Description of the Related Art
A device for displaying a backward view field of the vehicle in a monitor is conventionally proposed when no driver can see a place as a target at a dead angle of the vehicle at a retreating time of the vehicle. For example, Japanese Patent Publication No. 2-36417 discloses a backward monitor device of the vehicle comprising a television camera for photographing a backward portion of the vehicle, a monitor television for displaying a picture image picked up by this television camera, a sensor for outputting an information signal relative to a tire steering angle, and a circuit for generating a marker signal according to the information signal from this sensor and superposing and displaying a marker on the television screen. In this device, steering angle data of the tire and marker position data along a backward direction of the vehicle corresponding to this steering angle are stored in a ROM. A predicting backward locus of the vehicle according to the steering angle at that time is superposed on the picture image picked up by the television camera and is displayed on the television screen as a series of markers.
In accordance with such a device, the view field of a backward road situation, etc., and the predicting backward locus of the vehicle according to the steering angle are displayed on the screen of the monitor television at a backward moving time of the vehicle. Therefore, the driver can retreat the vehicle by operating the steering wheel while the driver sees the television screen without turning the driver""s head backward.
For example, in a column parking case, the vehicle is retreated in parallel with the road, and the steering wheel is turned in a suitable position so that the vehicle is advanced into a parking space. Further, it is necessary to turn back the steering wheel in a reverse direction, and guide the vehicle to a parking position as a target. However, in the conventional backward monitor device, it is difficult for the driver to judge a starting position of the turning of the steering wheel, a turning-back position of the steering wheel, and the degree of a steering amount by only seeing the backward view field and the predicting backward locus of the vehicle on the television screen. Accordingly, a problem exists in that no monitor device can sufficiently support the column parking.
To solve such a problem, an object of the present invention is to provide a steering assist device at a parking time in which a driver can easily grasp steering timing and a steering amount at a backward parking time.
Further, another object of the present invention is to provide a steering assist device which, at a parking time, can confirm whether a self-vehicle interferes with an obstacle or not.
To achieve the above objects, the present invention resides in a steering assist device comprising: a camera for photographing a backward portion of a vehicle; a monitor arranged in a driver""s seat of the vehicle; a steering angle sensor for detecting the steering angle of a steering wheel; and display control means for displaying a picture image provided by said camera in said monitor at a retreating time of the vehicle, and superposing and displaying a guide display for supporting driving of the vehicle at a parking time on a screen of said monitor, the steering assist device being characterized in that said guide display including: a steering start guide line fixedly displayed in a predetermined position on the screen of said monitor for guiding a steering start spot for parking; an eye mark fixedly displayed in a predetermined position on the screen of said monitor for guiding a turning-back spot of the steering wheel; and a steering amount guide mark moved and displayed along said steering start guide line on the screen of said monitor in accordance with the steering angle of the steering wheel detected by said steering angle sensor, said steering amount guide mark including a predicting parking area when the vehicle retreats and parking is completed with maintaining the steering angle of the steering wheel detected by said steering angle sensor, said steering amount guide mark being changed in size on the basis of far and near sense according to the steering angle.